Chapman (5-5) hadn't blown a save chance since June 24, putting together a club-record streak. He had it broken by a player who was out of the starting lineup because of a sore left wrist.

Shockingly, the 95-loss Astros were the last ones celebrating.

"He showed he's not perfect," Reds manager Dusty Baker said. "He's been as near perfect as anybody for the last two months.

"It was just their night."

Tyler Greene and J.D. Martinez singled off Chapman with one out in the ninth. Up came Dominguez, who was out of the starting lineup because of the sore wrist but got into the game after second baseman Jose Altuve got hurt.

He fouled off a 98 mph fastball, then connected on one at 98 mph for his second career homer.

"There's nothing else you can really look for," Dominguez said. "He got a fastball up in the zone. I took a good swing at the first one and fouled it off. I happened to get the barrel on the second one."

It was the fourth homer allowed this season by Chapman, who is 35 of 40 in save chances overall. Chapman struggled to keep the ball down and didn't hit 100 mph on the radar gun while losing the lead.

"Some nights you don't feel as good as other nights," Baker said. "Some nights the ball comes out your hand nice and easy."

It was the sixth time the Reds' bullpen - the best in the NL - failed to close out a win for Homer Bailey, leaving him stuck at 10 victories. Bailey pitched into the seventh inning, giving up two runs on a first-inning homer by Justin Maxwell.

The Reds had Joey Votto back at first base for the second straight game. Votto missed 48 games because of torn cartilage in his left knee. He flied out and drew three walks, one of them intentional.

Although Votto was back, the Reds were missing the other side of the infield. Third baseman Scott Rolen had an MRI that found inflammation in his lower back and will miss at least a few games. Shortstop Zack Cozart was still bothered by a sore back, which he hurt on Tuesday.

Bailey and Harrell also went head-to-head on Saturday in Houston, each allowing one run and failing to get the decision. The Astros won it on an error in the ninth.

Maxwell's two-run homer on Friday was a familiar development in a couple of ways. Maxwell's solo homer accounted for the only run Bailey allowed last Saturday in Houston.

"It was a slider that came out of my hand wrong," Bailey said. "It happens. He put a good swing on it and he should have."

Maxwell has 14 homers this season, eight in games in which Harrell pitched.

The Reds opened the bottom of the first with two singles and a four-pitch walk to Votto. Ludwick singled to tie it 2-all.

"I felt like I was awful today," said Harrell, who gave up seven hits and walked four in six innings. "I couldn't throw pitches where I wanted."

Chris Heisey tripled in the fifth inning and scored on Bruce's opposite-field single, giving the right fielder a seven-game hitting streak. Heisey had three hits overall.

Notes: Astros 3B Brandon Laird got sick before the game, prompting the Astros to give Matt Downs his 11th start at the position. 3B Scott Moore was out with a strained groin, and Dominguez had the sore left wrist. Dominguez got into the game in the third inning after Altuve left with a strained abdomen, forcing Downs to move to second base. ... Downs had a 13-pitch at-bat before striking out in the sixth. ... Reds 3B Todd Frazier has reached base in each of his last 29 games, passing Votto for the longest streak by a Red this season.